It’s understood that both John Booth and Graeme Lowdon have resigned from the Manor F1 team.

There has been no confirmation from the team, and both men are still working in Mexico this weekend and will stay until the end of the season.

It’s believed that the pair have lost faith in the ability of current owner Stephen Fitzpatrick and his business partner Abdulla Boulsien to keep the team alive long term.

While the team has created a potentially attractive package by signing contracts with Mercedes and Williams (for gearboxes and other technology) the financial future remains uncertain.

Aside from the $50m of ‘Bernie money’ there has been very little investment from Fitzpatrick this year. Meanwhile the owners have turned down offers from at least two new investors – sources suggest figures of $50m and $40m respectively – presumably on the basis that they can hold out for more.

Given that most of the staff have long links with Manor and have stayed loyal to the current management it remains to be seen how many will opt to stay on.

It’s looking more and more like the sport could lose 4 or even 5 teams at the end of this season.

Without engines that’s 2 Red Bull teams gone, without a Renault buyout Lotus won’t make it, Manor is looking questionable, Force India are already asking for some of their 2016 prize money and the 2015 season hasn’t finished, and Sauber is probably not far behind them …

Not to take away from your valid observation, but in the case of Force India I believe they are asking Bernie for an advance against 2015 earnings so they can spend now so that their 2016 car gets introduced at commencement of next season and not a delayed intro like happened in 2015.